17 March 2012

A massive asteroid that may be on a collision course with Earth should be studied in more detail, according to a former Apollo astronaut who specializes in monitoring potentially hazardous space rocks.
Asteroid 2011 AG5 has been the object of attention because scientists say it may swing close to our planet in the year 2040.
The big space rock is on NASA’s impact hazards list, but more definitive tracking of the object is still needed, scientists say. In fact, some near-Earth object (NEO) experts say it’s time to start hammering out a plan in case the asteroid needs to be deflected.
Former Apollo astronaut Russell Schweickart is calling upon NASA to undertake a detailed engineering and mission planning analysis of 2011 AG5.

A massive asteroid that may be on a collision course with Earth should be studied in more detail, according to a former Apollo astronaut who specializes in monitoring potentially hazardous space rocks.

Asteroid 2011 AG5 has been the object of attention because scientists say it may swing close to our planet in the year 2040.

The big space rock is on NASA’s impact hazards list, but more definitive tracking of the object is still needed, scientists say. In fact, some near-Earth object (NEO) experts say it’s time to start hammering out a plan in case the asteroid needs to be deflected.

Former Apollo astronaut Russell Schweickart is calling upon NASA to undertake a detailed engineering and mission planning analysis of 2011 AG5.

In a March 3 open letter to NASA administrator Charles Bolden, Schweickart spotlighted what he sees as the potential deflection challenges posed by asteroid 2011 AG5, should the object happen to be headed for a so-called keyhole in 2023, setting up a possible impact with Earth in 2040. [The 7 Strangest Asteroids in the Solar System]

Keyholes are small regions in space near Earth through which a passing NEO may be perturbed — due to gravitational forces — placing it onto a path that would strike Earth.

In this most recent communiqué, Schweickart questioned a view held by Bolden from an earlier exchange of letters between the two that a Deep Impact-like intercept of asteroid 2011 AG5 could be staged in enough time to derail a space rock from hitting Earth.

While Deep Impact was a very successful mission, it is a poor analogy for the potential deflection challenges presented by 2011 AG5, Schweickart noted. To depend on such an impact mission to justify waiting until after the next tracking opportunities — before doing any further engineering analysis — is ill advised, he said.

Schweickart contends that a 2011 AG5 deflection campaign requires two missions, not one, as was used on Deep Impact. In addition, intercepting and impacting 2011 AG5 presents far more daunting challenges than was posed by comet Tempel 1.

In his open letter, Schweickart told Bolden that, "neither you nor I would have risked our lives without solid engineering having gone into our respective missions. In this instance again, there are potentially lives at stake, and I know you take that responsibility seriously, as do I." [Photos: Asteroids in Deep Space]

"To be clear, what I am asking for is specific engineering and mission planning analysis to be performed now in order to insure that we fully understand the timeline requirements, in the unlikely event that AG5 should be headed for the 2023 keyhole," Schweickart wrote.

"We all realize it is highly likely that AG5 is not headed for an impact. But we must also hedge against the possibility that this will not be the case by being prepared to act, and not find ourselves awkwardly beyond the point where deflection remains an option," Schweickart concluded in his open letter to the NASA chief.

NASA's response

In response to the letter, Schweickart told SPACE.com that a NASA-organized teleconference was held on March 8 involving himself, as well as John Grunsfeld, NASA's Associate Administrator for the Science Mission Directorate, Jim Green, Director of Planetary Science, and Lindley Johnson, NEO Observations Program Executive.

"It was a very constructive discussion and as a result we will be getting together in the next few weeks to discuss the various issues and options which would apply to a variety of future scenarios regarding 2011 AG5," Schweickart said. "I’m looking forward to these substantive discussions and I commend John Grunsfeld and NASA for this positive response."

Schweickart's new letter to Bolden, "presents points we at NASA have considered in looking at the 2011 AG5 scenario," Lindley Johnson told SPACE.com.

"A big concern with any mission analysis is that they are only as good the initial input conditions. The results you obtain are always dependent on those conditions," he said.

Johnson said that if 2011 AG5’s orbit model in hand now turns out to be a good representation of where the NEO will be in the future, then a mission analysis could be done now, and such work would be worthwhile. [5 Reasons to Care About Asteroids]

But, if the asteroid’s orbit isn’t that well defined, then a mission analysis would need to be mostly re-done after a better orbit is ascertained, he said.

"We are certain we will have a higher confidence model after observations are collected in another orbit of AG5," Johnson said, "and we are confident we will have more than sufficient time to do both the mission analysis and undertake any response still necessary after that observation opportunity."

"However, we will continue to study the AG5 situation, as we do continuously for all objects on theimpact hazards list," Johnson concluded.

Tools to monitor 2011 AG5

"There are logical reasons to start really planning to do something really soon … and analyzing AG5 really soon," said Clark Chapman, a noted specialist in asteroids and a planetary scientist at the Southwest Research Institute in Boulder, Colo.

It has been generally thought that 2011 AG5 can't be observed again until September of 2013, Chapman told SPACE.com. "That’s not true. We can see it again in August of this year."

What’s needed is one of the largest ground-based telescopes on Earth, or the Hubble Space Telescope, Chapman advised. Doing so wouldn’t be too easy, "but in all probability could be done."

For one, the asteroid is very faint and ground-based telescopes would need to slew toward the horizon in a really dark sky.

"Telescopes are sort of designed to look more or less up … rather than over," Chapman noted. In the case of the Hubble Space Telescope, caution is the rule as it would be necessary to point the scope 42 degrees away from the sun to observe 2011 AG5, "but exceptions have been made in the past."

Odds of an impact

Still, whether using these tools to eye the asteroid will improve our understanding of the asteroid's track isn’t a given.

"We simply don’t know whether observations in August can make that much of a difference … but that's another arena in which studies should be done in the very near term," Chapman said.

In the meantime, more information about 2011 AG5 is needed, Chapman said.

"We don’t know how big this thing is," he said. "And if it’s on the big side, it would be hard to move it away from the keyhole with only a few years planning. And if it’s really big, it’s hard to move it away from the Earth if it goes through the keyhole."

Chapman stressed that the most probable result of more tracking of the asteroid is that the 2040 impact of Earth probability will drop to zero.

"I’m of the view that you can’t say, 'let’s just wait and the odds are likely to go to zero.' Yes, the odds are likely to go to zero…but suppose they don’t," Chapman said.

Leonard David has been reporting on the space industry for more than five decades. He is a winner of last year's National Space Club Press Award and a past editor-in-chief of the National Space Society's Ad Astra and Space World magazines. He has written for SPACE.com since 1999.

Looking for interplanetary defense work?

2:30 pm, March 14, 2012Updated: 2:31 pm, March 14, 2012

We were shocked to read on Discover magazine’s website last week that an asteroid 450 feet across, lurking just now on the other side of the sun, stands a (remote) chance of smacking us — or someone else on earth — in about 29 years. Scientists presently judge the probability to be around 1 in 625, which seems like a substantial upgrade from the usual estimate of a one in 5,000 chance that a major asteroid will hit Earth in the next century.

More will be known next year, after new calculations, and everything hinges on the asteroid — with the mild name of AG5 — passing through what astronomers are calling a space “keyhole” that could bend its orbit toward earth sometime in 2023. So there will be some time to prepare. But frankly we can see the opportunity for some defense industry contracts right now, and it’s not hard to pick out a front-runner.

With uncanny foresight, some scientists from Los Alamos National Laboratory prepared a video that was uploaded to YouTube in the middle of last month extolling how their newest Cray supercomputer can model the impact of an “energy source” on an asteroid. Robert P. Weaver, identified only as an R&D scientist at the New Mexico lab, narrates how the shock wave from a one-megaton-sized explosion — he never mentions the “n” word, for the nuclear weapons at the heart of the lab’s work — would blast a much larger asteroid into smaller bits of rock.

There’s no discussion about the consequences of creating so much debris in space, where the clutter is already threatening satellites and the space station. But it’s good to know we might not be defenseless. NASA has actually studied what’s engagingly called “planetary defense,” but so far it has deflected, so to speak, a call from former astronaut Rusty Schweickart to begin a special study of the threat of attack by the rock known as AG5.

Asteroid Will Pass Closer To Earth Than Many Satellites--Discovery Enabled by Planetary Society Grant

In less than a year, an asteroid that is half the size of a football field will pass within just a few thousand miles of our planet. The discovery of this object, dubbed 2012 DA14, was made possible by a Shoemaker Near Earth Object (NEO) grant provided by the Planetary Society.

The giant space rock was discovered on February 22, 2012 by La Sagra Observatory in southern Spain. One of the observatory's telescopes had recently been upgraded through the Planetary Society grant. Its new camera enabled detection of fast moving objects like 2012 DA14 – requiring very fast imaging for discovery and determination of their paths. The upgraded instrument has far outperformed the Observatory's other telescopes. It has found more than ten NEOs, along with a previously unknown comet.

At fifty meters across, 2012 DA14 is similar in size to the object that caused the Tunguska air burst over Siberia in 1908, leveling 2,000 square kilometers of forest. Fortunately, there is no danger of impact during the next pass of 2012 DA14.

“This asteroid is a wakeup call for the importance of defending the Earth from future asteroid impacts,” says Bill Nye, Chief Executive Officer of The Planetary Society. “Big impacts don’t happen often, but they will happen.”

2012 DA14 will come closest to Earth on February 15, 2013. It will zoom to within about 3.5 Earth radii or about 22,500 km from the Earth’s surface, well within the orbit of geostationary communications satellites (35,800 km). Current estimates are that it will be about magnitude 7 in brightness – not quite visible to the naked eye, but within reach of binoculars or a small telescope. It will fly across the sky at about one Moon diameter per minute.

Additional follow-up by observers around the world has resulted in this accurate prediction of the asteroid's current orbit by scientists at the Jet Propulsion Laboratory's Near Earth Object Program Office. Knowing the close approach is coming will allow astronomers to study the characteristics of the asteroid. A major goal will be greater refinement of its orbit so that future close approaches and even possible impacts can be predicted and prepared for.

Jaime Nomen and his colleagues at La Sagra Observatory have introduced observing strategies designed to improve the probability of discovering asteroids that larger surveys may miss. Nomen reports, “We try to find smaller objects located close to Earth that generally move at high angular speed. They may appear anywhere in the sky, even if that sky region had already been thoroughly searched just days before.”

The strategy paid off. With the new CCD telescope camera configured to shoot rapid, short exposures, Nomen and his colleagues captured 2012 DA14 as it moved across the sky at almost 11 arcseconds per minute. This is slower than a satellite but quite fast for a NEO. It's equivalent to a lunar diameter every three hours. The asteroid was already heading away from Earth after passing the planet about a week before, and at much greater distance than next year's encounter. Its path across the eastern sky, fast angular motion, quite faint (and fading) brightness, and high declination (far above the ecliptic plane in which most of the planets travel) could easily have allowed 2012 DA14 to escape undetected.

Planetary Society Gene Shoemaker grants are awarded to amateur observers, observers in developing countries, and professional astronomers who, with seed funding, can greatly increase their programs' contributions to NEO research. The program, begun in 1997, is named for Gene Shoemaker, a highly respected leader in the study of impact structures, and an advocate for NEO discovery and tracking programs.

The Planetary Society supports several projects that are helping to find near Earth objects and test techniques that may allow humanity to deflect a NEO that is headed toward a potentially catastrophic impact. The Society is committed to planetary defense. "Discovery, follow-up, and characterization of asteroids enabled by our Shoemaker grants is one of our most gratifying rewards,” says Bruce Betts, the organization's Director of Projects. “We want to help humanity avoid the world’s only preventable natural disaster. Astronomers like those at La Sagra Observatory are critical to that goal. Their discovery and next year's close approach will result in a scientific and planetary defense treasure trove of data.”

The 2012 DA14 flyby in 2013 will also serve as a warm-up for a similar fly by in 2029 by the much larger Apophis, a 270-meter asteroid co-discovered by Shoemaker NEO grant winner Roy Tucker.

10 March 2012

From:http://www.spaceref.com/news/viewnews.html?id=1620A third, and perhaps most important, reason for human asteroid missions is planetary defense: protecting the Earth from collisions with asteroids. That conjures up scenes from sci-fi movies like Armageddon and Deep Impact, but Jones notes the danger of such collisions is very real. "Our very survival as a human species depends on us being able to operate on these bodies and learn how to manipulate them," he said.

09 March 2012

"The door to peaceful nuclear explosions should not be closed, at least not now," the Foreign Ministry said the day before Mr. Yeltsin's arrival for three days of meetings in China... China is arguing that mankind needs to keep developing "peaceful" nuclear weapons in case a giant asteroid is discovered careering through space on a collision course with the earth..."Only China is thinking about the future of mankind," said a European diplomat here, rolling his eyes, as he repeated the Chinese argument that nuclear detonations might be needed on -- or above -- the planet."

"The issue of asteroid collisions is one that must be studied and great care must taken in order to ensure that the best possible solutions are being explored. What we cannot afford is an imperialist attitude towards the issue of collision prevention. The security of the planet is the responsibility of all of us," said a spokesperson for the Chinese government. "While we support the discussion revolving around this issue, we cannot in good faith simply agree to enter into the discussion about how to prevent this potential disaster until we discuss the criteria on which the discussion will take place." ... "We cannot allow the defence of Earth be the sole domain of Anglo-American interests. The defence of our planet must be a co-operative effort conducted by leading scientists from across the globe including Russia, which was the first country to launch a satellite into space and the first country to launch a human being into space. No asteroid protection can be conducted without Russian inclusion," said a spokesperson for the Kremlin. "The Americans and the British cannot seek dominance of space, neither in near orbit, the moon, or in any asteroid body. We cannot allow foreign interests to conduct weapon tests in space, nor allow them to push or drag meteors towards or away from the Russian people."

06 March 2012

Today, Mars is bone-dry; it once had running water. "Something bad happened there as well," he says. "Asteroids have us in our sight. The dinosaurs didn't have a space program, so they're not here to talk about this problem. We are, and we have the power to do something about it. I don't want to be the embarrassment of the galaxy, to have had the power to deflect an asteroid, and then not, and end up going extinct. We'd be the laughing stock of the aliens of the cosmos if that were the case."

The possibility of asteroids hitting Earth is actually a reasonably serious problem that does need a solution, Tyson contends. The asteroid Apophis, named for the Egyptian god of death and darkness, has a very slim chance of striking Earth in 2036. Tyson says some researchers have advocated for blowing up the football stadium-sized object.
That could create a bigger problem, though: "If you blow it up and it becomes two pieces, and now one is aimed for each coast of the United States, it's just doubled the emergency status of that call," he says.
Another option is what he calls a "gravitational tractor beam." A space probe would be parked a fixed distance away from the asteroid. Gravity would tend to pull the objects together, but by firing rockets on the probe, the asteroid would actually be "towed" away.
Tyson admits that such a space tow truck would be a tough sell for a president asking for more money for NASA.

03 March 2012

Kare's paper suggests that laser launch could meet the launch rate and cost to make SBSP feasible and economical.

http://fennetic.net/irc/897Kare-modular-laser-launch.pdf

However, we estimate that with plausible assumptions, even the “full up” cost of laser launch, including vehicles, operations and maintenance, and capital amortization, can easily be below $220/kg ($100/lb), provided the launcher is used at a reasonable fraction of its full capacity.

Space-based solar power (SBSP) is a concept for a revolutionary energy system. It involves placing into orbit stupendously large orbital power plants—kilometers across—which collect the sun’s raw energy and beam it down to where it is needed on the earth. In theory, SBSP could scale to meet all of humanity’s energy needs, providing virtually unlimited green, renewable power to an energy-hungry world.

Most renewable energy schemes sufer from intermittency and low energy density, requiring vast amounts of land and extensive storage as well as fossil fuel backup systems. Not so with SBSP systems. When placed in orbit where the sun shines constantly, they can deliver stable, uninterrupted, 24-hour, large-scale power to the urban centers where the majority of humanity lives. A network of thousands of solar-power satellites (SPS) could provide all the power required for an Earth-based population as large as 10 billion people, even for a fully developed “irst world” lifestyle but without the environmental downsides of nuclear or coal.

Should space-based solar power have a role in the US grand strategy for space? Should Airmen advocate for a US program in SBSP? Depend­ing on your viewpoint, SBSP is either the most important space project of our generation—critical to securing American long-term interests and requiring the advocacy of Airmen—or a fool’s errand, an impossible dream threatening to divert valuable resources from where they are most needed today